Anyone know this amp kit?
LM3886*3 Amp + Power supper kit/DIY - eBay (item 320464946907 end time Nov-14-10 23:03:59 PST)
How good is it? And is the amp kit reliable?
LM3886*3 Amp + Power supper kit/DIY - eBay (item 320464946907 end time Nov-14-10 23:03:59 PST)
How good is it? And is the amp kit reliable?
Since the seller has put up his email address, why not request a schematic of the paralleled amp from him? Things to check are that close tolerance parts are used in the gain networks - there are trimmers on the board but those might be for offset trimming purposes. If the design is based on National's AN-1192 it might have problems. The price looks reasonable given the 1off price of LM3886 is around $7.
i have used the bare pcb's from the seller in my build.
the schematic looks like this one:
DIY BPA300 6x LM3886 300W audio Amplifier
i would however not trust the gain and feedback resistors and if you buy the complete kit change them out with decent 0.1% items.
also i felt that C2 capacitor(as per link schematic) was far to big a size and would cut into audio spectrum. You can change these to around 10pF.
Without those 3 capacitors the board immediately oscillated i found in my testing. and made the zobel resistor smoke
the schematic looks like this one:
DIY BPA300 6x LM3886 300W audio Amplifier
i would however not trust the gain and feedback resistors and if you buy the complete kit change them out with decent 0.1% items.
also i felt that C2 capacitor(as per link schematic) was far to big a size and would cut into audio spectrum. You can change these to around 10pF.
Without those 3 capacitors the board immediately oscillated i found in my testing. and made the zobel resistor smoke
Ebay seller
I think this is the seller I had a problem with.
I ordered several LM3886 and power supply PCB's to make 2x 5-channel amps.
None of them worked at first...
There was no through-hole plating on one end of C7 (the input cap).
I tried complaining but couldn't get my message through - Language problem!!!
Gave up in the end and just soldered the lead both sides.
The boards were good quality apart from that. I can't beleive no-one else noticed
Frank
I think this is the seller I had a problem with.
I ordered several LM3886 and power supply PCB's to make 2x 5-channel amps.
None of them worked at first...
There was no through-hole plating on one end of C7 (the input cap).
I tried complaining but couldn't get my message through - Language problem!!!
Gave up in the end and just soldered the lead both sides.
The boards were good quality apart from that. I can't beleive no-one else noticed
Frank
If you ask the seller nobody has ever had a problem with anything 
I have only purchased two boards like this and assembled them with high quality components.
NOS MKC caps and LM3886 ordered directly from manufacturer.
They have an enormous amount of detail and dynamics for the price (and simplicity).
I am anyway going to sell my amp because they sound too bright for me.
I mostly use amps designed by Mr. Pass
In general Chinese PCBs are good (might have some mistakes like turning pot counter-clockwise increases volume) but their soldering and fake components are crap.
A kit that you assemble yourself lets you replace bad components easily and your soldering is most probably much better than Chinese soldering
I have only purchased two boards like this and assembled them with high quality components.
NOS MKC caps and LM3886 ordered directly from manufacturer.
They have an enormous amount of detail and dynamics for the price (and simplicity).
I am anyway going to sell my amp because they sound too bright for me.
I mostly use amps designed by Mr. Pass
In general Chinese PCBs are good (might have some mistakes like turning pot counter-clockwise increases volume) but their soldering and fake components are crap.
A kit that you assemble yourself lets you replace bad components easily and your soldering is most probably much better than Chinese soldering
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